1. Field of the Invention
The present invention relates to a photosensor chip package structure, particularly to a package structure of a photosensor chip containing an ambient light sensing unit and a proximity sensing unit.
2. Description of the Related Art
More and more sensors are used by consumer electronics, such as mobile phones, to save energy and improve human-machine interaction. For example, the latest mobile phones use as many as more than ten sensors. Therefore, engineers are eager to integrate sensors so as to save energy, space and cost.
The ambient light sensor is used to detect variation of ambient light so as to regulate brightness of the screen of a mobile phone. When the ambient light dims, the screen of a mobile phone also dims lest the light of the screen dazzle the user. When the ambient light brightens, the backlight of the screen also brightens to enhance visibility of the articles presented on the screen. Therefore, the ambient light sensor can save energy and increase the running time of a mobile phone. The proximity sensor is a non-contact object-detection sensor. In mobile phones, the proximity sensor is used to disable the touch control function when the user is talking with a contact. As soon as the user's head approaches the earpiece, the touch control function is automatically turned off lest the touchscreen operate erroneously by touching the user's face. As both the ambient light sensor and the proximity sensor are optical systems, they are normally encapsulated in an identical package structure so as to share the space, materials, wiring and power source.
Refer to FIG. 1 for a conventional photosensor chip package structure, wherein an IR LED (Light Emitting Diode) 14 and a sensor 13 containing an ambient light sensing unit 10 and a proximity sensing unit 12 are encapsulated inside a package 16 to form the so-called three-in-one package structure, whereby is decreased the space occupied by the package 16 and reduced the complexity of system design. The IR LED 14 emits infrared light. The infrared light is reflected by an object approaching the mobile phone and received by the proximity sensing unit 12. The proximity sensing unit 12 operates as soon as receiving the reflected infrared light. However, infrared light is also projected from the lateral sides of the IR LED 14, interfering with the normal light signal. Therefore, various thick light-blocking materials and package designs are used to form a light blocking wall 18 preventing from the interference between the sensor 13 and the IR LED 14. Further, the spacing between the sensor 13 and the IR LED 14 is also increased to achieve the same objective. However, the thick light-blocking material and the increased spacing make the area of the package structure hard to reduce. Besides, the light-blocking material increases complexity of the package structure.
Accordingly, the present invention proposes a novel photosensor chip package structure to solve the abovementioned problems.